Rubber composition and method of preserving rubber



Patented July 4, 1933 came STATES i 1,916,285 PATENT oFFIcE- COMPANY, OF NEw'YORK N. Y., A CORPORATION OF NEW' YORK RUBBER COMPOSITION AND METEOD OF PRESERVING- RUBBER No Drawing.

This invention relates to the art of preserving rubber, either in the vulcanized or unvulcanized condition, and to rubber compositions so preserved.

It is well known that rubber is subject to more or less rapid deterioration upon aging, especially. when exposed to light, heat, or air. .lt has been proposed to treat rubber with socalled anti-oxidants or age-resisters for the purpose of retarding its deterioration and extending the period of its usefulness. Such previously known anti-oxidants include phenolic compounds, aromatic amino compounds, and the condensation products of aldehydes and amines.

This invention consists in treating rubber with a member of a new class of age-resisters, the said class comprising secondary amines, one of the substituents of which is a monovalent aliphatic hydrocarbon group while the other is an aromatic group containing more than one aromatic ring. The aliphatic group may be any straight or branched chain aliphatic hydrocarbon group, or alicyclic group, and may even contain aromatic rings remote from the point of attachment as in the benzyl group. The aromaticgroup may contain two or more aromatic rings, conjugated, adjacent or indirectly joined one to another. Thus, the class includes such substances as methylalpha-naphthylamine, methyl-beta-naphthylamine, methyl-anthracylamine, methylamino-biphenyl, methylamino-diphenylmethane,

methylamino-diphenyl ether, methylaminodiphenylamine, N methyl-N-beta-naphthylp-phenylene diamine, p-methylaminddiphenyl-p-phenylene-diamine, l-met-hylamino l-naphthol, p-methylamino-p-hydroxy diphenyl ether, p,p di-methylaminddiphenylamine, and the corresponding ethyl, butyl, amyl, heptyl, and other alkyl derivatives, as well as similar compounds containing other substitutent groups, such as the cyclo- ,iexyl and benzyl groups, which, although not strictly aliphatic in nature, undergo the characteristic reactions of and confer upon their compounds essentially the same properties as purely aliphatic groups; it being understood that the above-named compounds are merely illustrative of the scope of the class, and that many other related compounds are likewise included within the definition. Any one or a mixture of several of the above-mentionedclass of age-resisters may be incorporated 1n- Application filed November 4, 1929, Serial No. 404,868.

Renewed April 18, 1932.

to rubber or a rubber composition with beneficial effects on itsage-resisting properties, preferably from 0.2 to 5 parts by Weight to 100 parts of rubber being used.

Example 1.As a specific example of one embodiment of the method of this invention, a typical tire tread composition was prepared containing: blended plantation rubbers 100 parts by weight, sulfur 5.5 parts, zinc oxide parts, gas black 40 parts, mineral rubber 10 parts, palm oil 5 parts, heXamethylene tetramine 0.7 5 parts, and methyl-alpha-naphthylamine 1.90 parts. I The composition was thoroughly mixed, and vulcanizedin a press for 4L5 minutes at 145 C. (294 F.) to produce an optimum cur The rate of agingotthe vulcanized composition was determined by measuring its tensile strength and elongation before and after aging. The accelerated aging test was carried out in theGeer aging oven, in which samples were maintained at a temperature of C. (158 F.) in a constantly renewed stream of air, the results being recorded in the following table, in which T indicates ultimate tensile strength in pounds per sq. inch and E indicates ultimate elongation in per cent. of original length A similar composition without the methylalpha-n'aphthylamine deteriorated approximately twice as much in the same time.

Example 2.A rubber composition similar to that specified in Example 1 above but without the methyl-alpha-naphthylamine was divided into 5 portions, one of which was used as a control. To the others were added respectively 0.95 parts 0.5% of the weight of the composition) of ethyl-alpha-naphthylamine, 2-isoamyl-alpha-naphth lamine, cycloheXyl-alpha-naphthylamine, and benzylalphanaphthylamine. The compositions were vulcanized, and tested after aging in the Geer oven as described above, as well as after aging in the Bierer-Davis oxygen bomb, in which the samples were maintained in an atmosphere of oxygen at a pressure of B IARTON C. REED, OF CHARLESTON, WEST VIRGINIA, ASSIGNOR TO THE B. F. GOODRIOH 300 lbs. per sq. in. and at a temperature of C; The results are shown below:

Aginy tests of alloyZ-alpha-naphthg lamines From the examples given above it is evident that secondary amines of the above described class, namely those possessing the general type formula where R is an alkyl group and R is an aryl group containing at least two aromatic rings, are extremely effective in retarding the deterioration which rubber normally undergoes upon aging.

Obviously, the practice of this invention is not limited to the specific compositions given above, such compositions being merely illustrative of one manner of employing the age-resisters of this invention. The proportions of the constituents may be varied, or other substances may be substituted therefor, since this invention is applicable to pure rubber or rubber compositions of the most varied nature. The age-resisters may also be applied to unvulcanized or vulcanized rubber with good effect on the age-resisting properties of the rubber, such as by applying them to the surface of the rubber, as for example in solution, or in the form of a paste or emulsion.

It is to be understood that the term treating as employed in the appended claims is used in a generic sense to include either the incorporation of the age-resistors into the rubber by milling or similar process, or their addition to the rubber latex before its coagulation, or to the application thereof to the surface of a mass of crude or vulcanized rubber. The term rubber is likewise employed in the claims in a generic sense to include caoutchouc, whether natural or synthetic, reclaimed rubber, balata, gutta percha, rubber isomers and like products, whether or not admixed with fillers, pigments, vulcanizing or accelerating agents. The term aliphatic, unless otherwise limited, is to be understood as including all substituent groups which confer the characteristic properties of aliphatic compounds on their derivatives, as

opposed to aromatic groups which confer or their derivatives, and particularly as including all groups hereinabove referred to as aliphatic in nature. The term allryl designates a hydrocarbon radical derived from a paraffin hydrocarbon by removing one hydrogen atom therefrom, and the term aryl designates a hydrocarbon radical derived from an aromatic hydrocarbon by removing one hydrogen atom from an aromatic nucleus as distinguished from a side chain.

While I have herein disclosed certain preferred manners of performing my invention, I do not thereby desire or intend to limit myself solely thereto, for, as hitherto stated, the precise proportions of the materials utilized may be varied and other materials having equivalent chemical properties may be employed if desired without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R an aryl hydrocarbon group containing at least 2 aromatic rings.

2. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R an aryl group containing 2 conjugated aromatic rings.

3. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R: a naphthyl group.

4. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R, is a branched chain alkyl group and R a naphthyl group.

5. The method of preserving rubber which comprises treating rubber with Q-isoamylalpha-naphthylamine.

6. A composition of matter comprising rubber and a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R an aryl group containing different and distinctly aromatic properties 2 conjugated aromatic rings.

7 A composition of matter comprising rubber and a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R a naphthyl group.

8. A composition of matter comprising rubber and a substance of the general formula R11I\I-'-R2 v where R is a branched chain alkyl group and R a naphthyl group.

9. A vulcanized rubber composition resulting from the vulcanization of a mixture comprising rubber, a vul'canizing agent, an or-' ganic vulcanlzation accelerator, and'a substance of the general formula H v R 1 I.Rz where R is an aliphatic hydrocarbon group and R is an aryl group containing two directly connected aromatic rings.

10. A vulcanized rubber composition re sulting from the vulcanization of a mixture comprising rubber, a vulcanizing agent, an organic vulcanization accelerator, and

' isoamyl-alpha-naphthylamine.

11. The method of preserving rubber which comprises treating rubber with a substance of the general formula R l IR where R is a straight chain alkyl group and R: an aryl hydrocarbon group containing at least 2 aromatic rings. 7

12. The method of preserving rubber wh1ch comprises treating rubber with a substance of the general formula where R is a normal butyl group and B is an aryl group containing at least two aromatic rings. 3

13. A composition of matter comprising rubber and a substance of the general formula H v R 1 IR2 where R is a straight chain alkyl group and an aryl group containing atvleast 2 aromatic rings. p

14. A composition of matter comprising rubber and a sub-stance of the general for- 'mula i 1' 2 where R is a normal butyl group and R is an arylfgroup contammg at least two aromatic rmgs.

' 15. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a monovalent aliphatic hydrocarbon group and R an aromatic group containing at least2 aromatic rings.

16. The method of preserving rubber which comprises treating rubber with a substance of the general formula 5 u -n u where R is a straight chain alkyl group and R is an aryl group containing at least 2 conjugated rings.

17. The method of preserving rubber which comprises treating rubber with a substance of the general formula R1NR2 where R is a straight chain alkyl group and R is a naphthyl group.

18. The method of preserving rubber which comprises treating rubber with a monobutyl naphthylamine.

19. The method of preserving rubber which where R is an alkyl group and R is an aromatic group containing atleast 2 aromatic rings.

22. The method of'preserving rubber which comprises treating rubber with a substance of the general formula where R is a branched chain alkyl group and R is'an aromatic group containing at least 2 aromatic rings.

' 28. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a branched chain alkyl group and R is an aryl hydrocarbon group containing 2 aromatic rings.

24. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is an ethyl group and R is an aromatic group containing 2 aromatic rings.

25. The method of preserving rubber which comprises treating rubber with a sub stance of the general formula where R, is an alkyl groupand R is an aryl group containing 2 aromatic rings.

30. The method of preserving rubber which comprises adding to rubber latex a small proportion of a monoalkyl naphthylamine.

31. The method of preserving rubber which comprises adding to rubber latex a small proportion of ethyl beta-naphthylamine.

32. A composition comprising rubber and a substance of the general formula H il -1 1412 where R is a monovalent aliphatic hydrocarbon group and R an aromatic group containing at least 2 aromatic rings.

A composition comprising rubber and a substance of the general formula where R is a straight chain alkyl group and R is a naphthyl group.

34. A composition comprising rubber and a substance of the general formula RHLR.

Where R is a branched chain alkyl group and R is an aryl group containing at least 2 aromatic rings.

35. A composition comprising rubber and a substance of the general formula where R is a branched chain alkyl group and R is an aryl group containing at least 2 conjugated rings.

36. A composition comprising rubber and a substance of the general formula where R, is an ethyl group and R is an aromatic group containing 2 aromatic rings.

37. A composition comprising rubber and a substance of the general formula where R is an ethyl group and R is an aryl hydrocarbon group containing 2 aromatic rings.

38. A composition comprising a monoethyl naphthylamine.

39. A composition comprising ethyl beta-naphthylamine.

40. A composition resulting from the vulcanization of a mixture comprising rubber, sulphur, an active organic accelerator and a monoalkyl naphthylamine.

41. A composition resulting from the vulcanization of a mixture comprising rubber. sulphur, an active organic accelerator and n-butyl beta-naphthylamine.

42. A liquid latex composition comprising rubber latex and a substance of the general formula rubber and rubber and where R, is a monovalent aliphatic hydrocarbon group and R is an aromatic group containing 2 aromatic rings.

43. A liquid latex composition comprising rubber latex and a substance of the general formula H ant-'11.

where R, is a monovalent aliphatic hydrocarbon group and R is an aryl hydrocarbon group containing 2 aromatic rings.

44. A liquid latex composition comprising rubber latex and a monoalykyl naphthylamine.

45. A liquid latex composition comprising rubber latex and ethyl beta-naphthylamine.

In witness whereof I have hereunto set my hand this 11th day of October, 1929.

MARION G. REED. 

